Assembly and method for aerosol spraying a liquid product contained in a container and related container

ABSTRACT

An assembly for aerosol spraying a liquid product contained in a container includes a container of the disposable type containing only the liquid product to be aerosol sprayed and means for feeding into the container pressurised air with a constant pressure. The container includes a case on which an aperture is formed for feeding the pressurised air into the container. At a top portion of the case a valve for mixing the liquid product with the pressurised air so as to obtain an aerosol mixture and a nozzle for supplying the aerosol mixture are provided, the nozzle being mechanically and fluid-dynamically associated with the valve. The feeding of the pressurised air into the container is carried out both before the opening of the valve, that is in a step of loading the container, and while the valve is opened, that is during aerosol spraying of the liquid product.

DESCRIPTION

The present invention relates to an assembly for aerosol spraying a liquid product contained in a container.

The invention further relates to a container of a liquid product to be aerosol sprayed, as well as to a method for aerosol spraying a liquid product contained in a container.

Throughout the present description and in the attached claims, the term “aerosol spraying” is used to indicate the creation and the supply of a mixture of micro particles of liquid product dispersed into the air.

Containers for aerosol spraying liquid products such as paints, perfumes, insecticides, detergents, etc. are well known.

For example the so-called “spray cans” of the disposable type are common and widely used. These are cylindrical containers, made from tinplate or aluminium, which are filled with a mixture of a liquid product (for example paint) and with a liquid propellant consisting of a liquefied gas (for example propane, butane or isobutane). As an example, in a paint spray can of 400 ml, the aforementioned mixture can be formed by 200 ml of paint and 200 ml of liquid propellant.

The liquid propellant has the purpose of diffusing the liquid product in the form of aerosol.

Aerosol spraying of the liquid product by effect of the liquid propellant occurs at a mixing valve that is purposely provided in the spray can.

Due to the pressure exerted on the aforementioned mixing valve, the liquid propellant returns to the gas state and violently comes out from a supplying nozzle which is purposely provided in the spray can, bringing therewith also the liquid product which it was mixed with. The gas part of the mixture dissolves in the air separating from the liquid part, thus obtaining the aerosol spraying of the liquid product.

On the other hand, systems are known for supplying a liquid product in the form of an aerosol through supply of pressurised air, such as, for example, the aerographs. In such systems, a dispensing gun is coupled, through a connection hose, with a group for generating pressurised air which is typically arranged at a remote position with respect to the gun. Such a gun is moreover connected to a hose that draws from the container in which there is the liquid product to be aerosol sprayed. When the gun is actuated, a depression which draws the liquid product towards a supplying nozzle is created in the body of the gun, substantially due to the Venturi effect, by the supply of pressurised air. The pressurised air thus expels the liquid product through the supplying nozzle, without any mixing being created upstream of the nozzle itself.

U.S. Pat. No. 4,972,975 discloses a device for spraying a liquid product contained in a container made of plastic material. Such a container can be recharged many times with new liquid product. The supplying device comprises a group for generating pressurised air that is suitably connected to the aforementioned container. Such a group comprises a vane pump and a motor for actuating the aforementioned pump. The pressurised air is introduced in the container through a hose that is connected to a properly designed supplying nozzle. The supply occurs, upon actuating the motor of the vane pump, due to the pressure exerted by the user on the supplying nozzle. The pressurised air introduced in the container pushes the liquid product to go up through a suction hose until it reaches the nozzle, which causes it to be nebulised in the air. The interruption of the supply occurs by turning off the motor of the pump or, in a particular embodiment, by opening a vent hole properly created in the upper portion of the container.

The Applicant has found a number of drawbacks in the device described above, the first of which is the need to provide nozzles that are properly designed to obtain the nebulisation of the liquid product. Moreover, in the embodiment in which the interruption of the supply occurs by turning off the motor of the pump, when the motor is turned off there is a gradual and not instantaneous reduction of the supplied product, with negative consequences on the quality of the spraying. On the other hand, in the embodiment in which the interruption of the supply occurs by opening the vent hole, every time the vent hole is closed it is necessary to wait for the container to return to the desired pressure so as to be able to have an optimal spray. Moreover, the provision of the vent hole in the upper portion of the container actually prevents the device from being able to be used in positions that are different from the vertical one.

U.S. Pat. No. 5,046,667 discloses a spraying device that differs from that described in U.S. Pat. No. 4,972,975 in that it uses a slide valve which, in the position in which the button is pressed, allows the compressed air both to press on top of the free surface of the liquid product so as to allow the liquid product to go up into the suction hose and reach the supplying nozzle, and to reach itself the supplying nozzle, where the nebulisation between air and liquid product is created..

The Applicant has found that also in the abovementioned device it is necessary to provide nozzles that are properly designed so as to obtain the nebulisation of the liquid product. Moreover, the motor for actuating the pump is actuated only when the nozzle is open. This means that the container is never pressurised.

Basically, the Applicant has found that, differently from conventional spray cans, in the devices described in U.S. Pat. No. 4,972,975 and U.S. Pat. No. 5,046,667 there is no mixing valve upstream of the supplying nozzle and the supply of the liquid product in the form of aerosol occurs with dynamics which are comparable to those of aerographs. In particular, in the aforementioned devices the feeding of the pressurised air into the container occurs only during the supply of the product contained in the container.

U.S. Pat. No. 5,411,183 discloses a device for spraying a liquid or foam, that is provided with a pump that can be actuated manually and that is suitable for feeding pressurised air into a container. A dosing valve, through which the supply of liquid or foam occurs, is associated to the container. A one-way valve is placed between the pump and the container so as to avoid a flow of air from the container towards the pump. In an embodiment thereof which is suitable for professional applications, the feeding of the pressurised air into the container occurs by effect of a thrust action exerted by a motorised pump.

In such a device, the feeding of the pressurised air into the container occurs by arranging the container in a suitable loading station and, therefore, before the supply of liquid or foam. Analogous devices from this point of view are described in CH 632423, DE 3022913 and DE 8813663U.

The Applicant has found that in the devices described in the abovementioned documents the pressure of the air inside the container varies greatly during use precisely because of the supply itself. This generates a spray that is not uniform and/or homogeneous.

The Applicant has moreover found that in the devices described in the aforementioned documents it is necessary to reach particularly high pressures so as to ensure even a minimum useful life, thus leading to the use of pumps/motors that are extremely bulky and heavy, as well as expensive, and for this exact reason they are not suitable for being moved together with the container during the supply.

The Applicant has focused its attention on those aerosol spraying systems in which disposable containers provided with mixing valves, like for example conventional spray cans, are used. The Applicant has indeed verified that these systems of aerosol spraying ensure a constant pressure inside the container and, consequently, a spray that is almost instantaneous with optimal characteristics, without suffering from the drawbacks mentioned above with respect to the devices described in the aforementioned prior art documents.

There are however some drawbacks associated with the use of the aforementioned spray cans, related to the use as a propellant of a liquefied gas (for example propane, butane or isobutene) which, as it is known, is extremely inflammable. Moreover, such a propellant can form an explosive mixture with air, especially if it is released in closed or confined areas. There is also a risk of explosion of the spray, in those cases in which there is a strong overheating which causes a considerable increase in volume and pressure of the propellant. Finally, the user could suffer serious cold injuries, in those cases in which the propellant comes into contact with his eyes and skin.

Spray cans should therefore be handled, transported and stored with certain care.

The technical problem at the basis of the present invention is that of aerosol spraying a liquid product contained in a container in an almost instantaneous manner, with a constant pressure and having optimal spray characteristics, without moreover using liquid propellants, so as to avoid the aforementioned drawbacks.

The present invention therefore, in a first aspect thereof, relates to an assembly for aerosol spraying a liquid product contained in a container, said assembly comprising a container of the disposable type containing only the liquid product to be aerosol sprayed and means for feeding pressurised air into said container, in which the container comprises a case on which an aperture is formed for feeding said pressurised air into the container and, at a top portion of said case:

-   -   a mixing valve for mixing said liquid product with said         pressurised air so as to obtain an aerosol mixture;     -   a supplying nozzle for supplying said aerosol mixture, said         nozzle being mechanically and fluid-dynamically associated with         said valve;

characterised in that said means are adapted to feed pressurised air into said container with a constant pressure both before the opening of said mixing valve and while said mixing valve is opened.

Throughout the description and in the following claims, the term “container” is used to indicate any kind of container for containing a liquid product. It can therefore be a can, a jar, a cartridge, etc. The liquid product can be of any kind, like for example paint, oil, chemical products of various kind, etc.

Advantageously, in the assembly of the present invention it is possible to aerosol spray the liquid product contained in the container in a manner that is completely similar to what occurs in a conventional disposable spray can, without however using any propellant. Therefore the risks related to the inflammability of the propellant are advantageously avoided.

Moreover, due to the absence of any propellant, the container of the invention can be filled substantially entirely with the liquid product to be aerosol sprayed. This implies lower costs for the user (since he will need to buy a smaller number of containers for the same amount of liquid product to be aerosol sprayed), and less “waste” of disposable spray cans, with obvious advantages in terms of pollution of the environment and lower costs for the disposal and recovery of the materials of the empty spray cans. Further advantages in terms of environment pollution are obtained thanks to the fact that the use of the assembly of the present invention does not cause any propellant to be dispersed into the environment.

The Applicant has found that keeping an almost constant level of pressure inside the container while aerosol spraying, and therefore obtaining a spray having the desired characteristics of uniformity, is ensured by the fact that the container continues to be supplied with pressurised air even while aerosol spraying the liquid product. This moreover makes it possible to be able to provide levels of pressure that are lower with respect to those required in devices in which the supply of the pressurised air occurs only before the step of aerosol spraying, with a consequent advantageous reduction of the size and of the weight of the means especially provided for supplying the pressurised air, which can thus be transported more easily during the aerosol spraying step. Of course, even the cost of the aforementioned means is advantageously low.

The Applicant has further observed that in the assembly of the present invention the characteristics of spray quality are independent from the temperature at which it happens, contrarily to the case of the conventional spray in which the optimal characteristics are obtained at temperatures of 20° C. and the variations of this parameter, affecting the physical characteristics of the expansion of the propellant gas adapted to create aerosol spraying, radically influence the quality of the result.

Advantageously, just like in conventional spray cans, it is possible to obtain the desired aerosol spraying depending on the type of liquid product to be aerosol sprayed by acting upon the structural characteristics of the mixing valve and possibly of the supplying nozzle. Therefore, it is possible to provide on each container the mixing valve (and possibly a supplying nozzle) that is most suitable according to the actual type of liquid product used.

Preferably, the aforementioned aperture is formed at said top portion of said case in a position so that, when the container is in a substantially vertical supplying position, it is above the free surface of the liquid product.

Moreover, the position of the aperture for feeding air is such that part of the air introduced in the container directly reaches the mixing valve and another part of the aforementioned air acts by pushing onto the free surface of the liquid product, which is thus forced to go up through a special suction hose until it reaches the mixing valve.

Preferably, a one-way valve is further provided, which can be coupled to said aperture and to said means for feeding the pressurised air.

Advantageously, the one-way valve prevents the liquid product from being able to flow out from the container through the aforementioned aperture. Therefore, the container of the invention can be used in any position, even with the axis of the container inclined with respect to the vertical or it can even be upside down.

In a first preferred embodiment of the assembly of the present invention, the aforementioned means for feeding the pressurised air comprise a hose which can be coupled, at a first free end thereof, to said one-way valve and, at an opposite free end thereof, to a group for generating pressurised air which is provided at a remote position with respect to said container.

Preferably, in such a case, said group for generating pressurised air is associated with a belt which can be put on by a user.

In a second preferred embodiment of the assembly of the present invention, the aforementioned means for feeding the pressurised air comprise a device for generating pressurised air which can be removably coupled to the container and a hose which can be coupled, at a first free end thereof, to said one-way valve and, at an opposite free end thereof, to said device for generating pressurised air, so that, when the device for generating pressurised air is coupled to the container and the hose is coupled to the one-way valve and to the device for generating pressurised air, the assembly forms a self-governing operative unit which can be gripped and moved by the user.

Advantageously, the same device for generating pressurised air can be used by the user each time associating thereto a plurality of different containers containing possibly different liquid products, such containers always being of the “disposable” type. In other words, the containers with the liquid products can be sold separately from the device for generating pressurised air, which the user needs to buy only once.

Preferably, said device for generating pressurised air is coupled with said container at a bottom surface of said case. In this way the user can grip and use the assembly of the present invention like if it were a conventional spray can.

Preferably, in all the embodiments of the present invention the group or device for generating pressurised air comprises a diaphragm pump. Advantageously, such a type of pump ensures that the pressure values required by the mixing valve are reached so as to achieve the desired aerosol spraying.

In a second aspect thereof, the present invention relates to a disposable container of a liquid product to be aerosol sprayed, comprising:

-   -   a case on which an aperture is formed for feeding pressurised         air into a container with a constant pressure and, at a top         portion of said case:     -   a mixing valve for mixing the liquid product with said         pressurised air so as to obtain an aerosol mixture to be fed         with a constant pressure;     -   a supplying nozzle for supplying said aerosol mixture, said         nozzle being mechanically and fluid-dynamically associated with         said valve.

Advantageously, such a container can be used in the assembly of the present invention described above.

Preferably, such a container has, individually or in combination, the structural and functional characteristics discussed above with respect to the container of the assembly of the present invention and, therefore, it has all the advantages mentioned above.

In a particularly preferred embodiment thereof, the aforementioned container comprises means for removably coupling to the aforementioned case a device for generating pressurised air so that the assembly consisting of said container and of said device for generating pressurised air constitutes a self-governing operative unit which can be gripped and moved by the user.

In a third aspect thereof, the present invention relates to a method for aerosol spraying a liquid product contained in a container, the method comprising the steps of:

-   -   providing a container of the disposable type containing only the         liquid product to be aerosol sprayed and provided with an         aperture for feeding pressurised air, a valve for mixing the         liquid product with air and a supplying nozzle;     -   feeding pressurised air into the container in order to push the         liquid product towards said valve for mixing the liquid product         with said pressurised air so as to obtain an aerosol mixture;     -   supplying said aerosol mixture with a constant pressure         simultaneously to feeding into the container said pressurised         air.

Advantageously, such a method can be actuated by using the assembly and/or the container of the present invention described above.

It therefore makes it possible to achieve all the advantages mentioned above.

Further characteristics and advantages of the present invention shall become clearer from the following detailed description of a preferred embodiment thereof, made with reference to the attached drawings and given for indicative and not limiting purposes. In such drawings:

FIG. 1 schematically shows a top side section view of an assembly for aerosol spraying a liquid product contained in a container, according to a first embodiment of the present invention;

FIG. 2 schematically shows a top side view of a container that can be used in the assembly of FIG. 1;

FIG. 3 schematically shows an exploded perspective view of a device for generating pressurised air that can be used in the assembly of FIG. 1;

FIG. 4 schematically shows a partial perspective view of a part of an alternative embodiment of the assembly of the present invention.

FIGS. 1-3 show an assembly for aerosol spraying a liquid product contained in a container, in accordance with the present invention. The assembly is wholly indicated with reference numeral 10, whereas the container is indicated with reference numeral 20. The liquid product is indicated with L, and it has a free surface P.

In the preferred embodiment of the present invention, said liquid product L is a paint. It is however obvious that in the present invention any other type of liquid product can be used.

The container 20 comprises a case 20 a that is preferably made of a metal material, more preferably carbon steel.

The container 20 is equipped with a mixing valve 22 which is fluid-dynamically and mechanically coupled with a supplying nozzle 24. The latter is in fluid communication with the liquid product L through a suction hose 26.

In accordance with the present invention, an aperture 28 is formed on the top portion of the case 20 a of the container 20. Such an aperture 28 is located at a portion of container 20 that is spatially separate from that in which the valve 22 and the nozzle 24 are provided.

The aperture 28 is placed above the free surface P of the liquid product L contained in the container 20, when the longitudinal axis X of the container 20 is in a vertical supplying position, i.e. it is arranged as illustrated in FIGS. 1 and 2.

More precisely, the container 20 illustrated in the non limiting example of FIGS. 1 and 2 substantially has the shape of a conventional spray can, i.e. it has a cylindrical body 30 that is closed at the bottom by a bottom surface 32 and at the top by a dome-shaped surface 34. The bottom surface 32 is concave, i.e. it bulges inwards with respect to the container 20, and the dome-shaped surface 34 is convex, i.e. it bulges outwards with respect to the container 20.

At the top of the dome-shaped surface 34 it is provided a seat 38 in which the valve 22 and the nozzle 24 are arranged, both absolutely identical to those used in conventional spray cans.

The valve 22 can be opened by pressing a button 36 located above it. By releasing the button 36, on which a return spring (not illustrated for the sake of simplicity) acts, the valve 22 closes, just like what occurs in conventional spray cans.

In detail, the container 20 of the present invention differs from that of a conventional spray can only for the fact that there is the aforementioned aperture 28. Such an aperture 28 is located at the dome-shaped surface 34 alongside the housing seat 38 of the valve 22 and of the nozzle 24. Advantageously, the provision of the aperture 28 in a position that is separate from that in which the nozzle 24 is provided makes it possible to obtain the desired aerosol spraying effect in the spray, differently from what occurs in devices that operate similarly to the aerographs.

The provision of such an aperture 28 does not considerably affect the production costs of a conventional spray can of the disposable type. The production of the container 20 of the assembly of the present invention can thus advantageously be made in a conventional production line of conventional disposable spray cans, implementing such a line with a special station for perforating the spray can.

In non operating conditions, the aperture 28 is closed by a special lid (not illustrated). Preferably, such a lid is screwed onto a threaded surface formed in the aperture 28.

In operating conditions, a one-way valve 40 is coupled to the aperture 28, preferably through respective portions of threaded surfaces.

In addition to the aforementioned container 20, the assembly 10 according to the present invention comprises a device 50 for generating pressurised air A. Such a device 50 is in fluid communication with the container 20 through a hose 52 for feeding pressurised air.

According to the invention, a free end 53 a of the hose 52 is coupled to the one-way valve 40 mounted on the aperture 28, whereas the opposite free end 53 b of the hose 52 is associated to the device 50.

The container 20 and the device 50 comprise respective means 42 for removably associating the device 50 to the container 20 so that the assembly 10 comprising the container 20 and the device 50 for generating pressurised air constitutes a self-governing operative unit that can be gripped and moved by a user.

The aforementioned means 42 preferably allow a mechanical coupling of the generating device 50 to the container 20. In the figures shown herewith, the means 42 comprise a circumferential groove 44 (FIG. 2) provided on a lower end portion of the cylindrical body 30 of the container 20, therefore at the bottom surface 32, and that snap-couples on an upper surface of the device 50 for generating pressurised air (FIG. 3).

Alternatively, the aforementioned means 42 are defined by elastic hooks.

In the specific embodiment shown in FIGS. 1 and 3, the device 50 comprises a case 56, closed at the bottom by a bottom 58 and on top by a cover 60.

The cover 60 comprises a circular recess 62 in which the lower end portion of the cylindrical body 30 of the container 20 is snap-coupled.

In an alternative embodiment of the present invention, the cover comprises a convex portion, i.e. that bulges outwards from the device for generating pressurised air, and is shaped to match the concave bottom of the container. Such a convex portion can contain magnets that ensure a sufficiently stable coupling with the bottom of the container.

The case 56 of the device 50 contains an air pump 64, an electric motor 66 which actuates the pump 64 and a group 68 for supplying power to the motor 66.

Preferably, the pump 64 is of the diaphragm type. There are diaphragm pumps currently on the market, which have technical characteristics so as to ensure the use in devices for generating pressurised air according to the present invention. In particular, 2.3-2.5 bar diaphragm pumps are for example used, which satisfy the requirements of constancy and regularity of aerosol spraying. Once it has been actuated, the diaphragm pump rapidly brings the air in the container 20 to the optimal pressure for aerosol spraying (about 3 seconds). For such a purpose the diaphragm pump is equipped with a system of valves on the delivery and suction sections which make it possible to not exceed the predetermined maximum pressure level, even in a condition of continuous use with the nozzle pushed.

The electric motor 66 can be actuated through a switch (not shown) preferably provided on the case 56.

The power supplying group 68 preferably comprises batteries of the rechargeable type. Recharging occurs through a conventional recharging device. Preferably, on the device 50 for generating pressurised air an indicator is provided which indicates the level of the battery charge, or rather, it signals when the batteries are almost flat.

As shown in FIG. 3, the case 56 (or at least one of the bottom 58 and the cover 60), comprises at least one hole 70 so as to allow the pump 64 to suck in air from the environment. A hose 72 for emitting pressurised air A, which passes through the case 56 via a special hole 74, is associated to the pump 64.

The hose 72 is in fluid communication with the hose 52 for feeding pressurised air, or alternatively the hose 72 is nothing but an end portion of the hose 52.

According to a further embodiment of the invention, the device for generating pressurised air, instead of being associated to the aforementioned container 20, can be a conventional group for generating pressurised air provided at a remote position with respect to the container 20 and connected thereto through a hose for feeding pressurised air. For example, an air compressor, or the compressed air line provided in an industrial factory, can be used.

Aerosol spraying of the liquid product L occurs in a manner that is substantially identical to what occurs in conventional disposable spray cans. The only difference is that while conventional spray cans also contain a propellant, the container 20 can be filled entirely with the liquid product L only, and pressurised air, which is supplied later on, is used as a vector.

Aerosol spraying the liquid product L thus initially provides for filling the container 20 with only the liquid product L.

Subsequently, pressurised air A is fed into the container through the aperture 28. One part of such pressurised air A acts upon the free surface P of the liquid product L, whereas a different part directly reaches the mixing valve 22.

By opening the valve 22, that is by pressing on the button 36 on the valve 22, the liquid product L goes up towards the mixing valve 22 through the suction hose 26. At such a valve 2 the mixing of the liquid product L with the pressurised air and therefore the aerosol spraying of the liquid product L occurs. The liquid product L can thus be supplied into the outside environment in the form of an aerosol through the nozzle 24.

Preferably, the feeding of pressurised air occurs by associating the device 50 for generating pressurised air to the container 20 beforehand (as described above and as illustrated in FIG. 3). Alternatively, the pressurised air can be made to come from a group for generating pressurised air provided at a remote position with respect to the container 20.

From what has been described above it should be understood how the use of the assembly 10 of the present invention for obtaining aerosol spraying of any liquid product L is completely comparable to that of a disposable spray can of the known type, where instead of using a liquid propellant as a vector for aerosol spraying, pressurised air that can be supplied to the spray can in any moment is used.

In the particular embodiment in which the device 50 is coupled with the container 20, the user during operation will grip and move the assembly consisting of a container 20 and a device 50 as if it were a conventional spray can.

He will simply have to activate the device 50 for supplying the pressurised air before actuating the supplying button 36.

The device 50 can be bought only once by the user, who will then be able to find the relative container on the market with the desired liquid product therein. Such a liquid product will be suitably studied and made so as to give it the best and most suitable chemical-physical characteristics to achieve the desired aerosol spraying. From this point of view, the choice of the mixing valve 22 (and possibly of the supplying nozzle 24) will be made bearing in mind the chemical-physical characteristics of the liquid product L of interest, being able in any case to limit the choice to components already available on the market, since they are used in conventional spray cans.

FIG. 4 illustrates a part of an alternative embodiment of the assembly of the present invention.

In such a figure, structural elements which are equal or corresponding to those described above with reference to FIGS. 1-3 are indicated with the same reference numeral and are not described again.

In the embodiment of FIG. 5, the container (not illustrated) is completely identical to the container 20 of FIGS. 1 and 2 with the sole exception that on the lower end portion of the cylindrical body 30 of the container 20, i.e. at the bottom surface 32, there are no means 42 for coupling to the device 50 for generating pressurised air. Indeed, in the embodiment of FIG. 5 the generating device 50 is provided, at the bottom 58 thereof, with loops 90 that are suitable for allowing the insertion of a belt 100 which can be put on by the user. In such a way, during use, the user only grips the container, whereas the device 50 for generating pressurised air remains anchored to the waist of the user.

The device 50 is otherwise absolutely identical to that of FIGS. 1 and 3 (although having a different shape and a different arrangement of the components provided therein), with the single further exception that on the cover thereof (not illustrated) there are no means for coupling to the container 20. In this case the switch for actuating the electric motor 66 is however visible (indicated with reference numeral 67). Alongside the switch there are also lights 67 a, 67 b that are suitable for indicating the actuation of the electric motor 67 and the charge level of the batteries (that is to indicate when the batteries are almost flat).

Of course, a man skilled in the art, with the purpose of satisfying contingent needs and specifications, may carry out numerous modifications and variants to the aforementioned invention, all moreover contained in the scope of protection of the present invention as defined by the following claims. 

1. An assembly for aerosol spraying a liquid product contained in a container, said assembly comprising a container of the disposable type containing only the liquid product to be aerosol sprayed and means for feeding pressurised air into the container, wherein the container comprises a case on which an aperture is formed for feeding said pressurised air into the container and, at a top portion of said case: a mixing valve for mixing said liquid product with said pressurised air so as to obtain an aerosol mixture; a supplying nozzle for supplying said aerosol mixture, said nozzle being mechanically and fluid-dynamically associated with said valve; wherein said means are adapted to feed pressurised air into said container with a constant pressure both before the opening of said valve and while said valve is opened.
 2. The assembly according to claim 1, wherein said aperture is formed at said top portion of said case in a position so that, when the container is at a substantially vertical supplying position, the aperture is above the free surface of the liquid product.
 3. The assembly according to claim 1, comprising a one-way valve which can be coupled to said aperture and to said means for feeding the pressurised air.
 4. The assembly according to claim 3, wherein said means for feeding the pressurised air comprises a hose which can be coupled, at a first free end thereof, to said one-way valve and, at an opposite free end thereof, to a group for generating pressurised air which is provided at a remote position with respect to said container.
 5. The assembly according to claim 4, wherein said group for generating pressurised air is associated with a belt which can be put on by a user.
 6. The assembly according to claim 4, wherein said group for generating pressurised air comprises a diaphragm pump.
 7. The assembly according to claim 3, wherein said means for feeding the pressurised air comprises a device for generating pressurised air which can be removably coupled to the container and a hose which can be coupled, at a first free end thereof, to said one-way valve and, at an opposite free end thereof, to said device for generating pressurised air, so that, when the device for generating pressurised air is coupled to the container and the hose is coupled to the one-way valve and to the device for generating pressurised air, the assembly forms a self-governing operative unit which can be gripped and moved by the user.
 8. The assembly according to claim 7, wherein said device for generating pressurised air comprises a diaphragm pump.
 9. The assembly according to claim 7, wherein said device for generating pressurised air is associated with said container at a bottom surface of said container.
 10. A disposable container for a liquid product to be aerosol sprayed, comprising: a case on which an aperture is formed for feeding into the container pressurised air with a constant pressure and, at a top portion of said case: a mixing valve for mixing the liquid product with said pressurised air so as to obtain an aerosol mixture to be fed with a constant pressure; a supplying nozzle for supplying said aerosol mixture, said nozzle being mechanically and fluid-dynamically associated with said valve.
 11. The container according to claim 10, comprising means for removably coupling a device for generating pressurised air to said case so that the assembly consisting of said container and said device for generating pressurised air forms a self-governing operative unit which can be gripped and moved by the user.
 12. A method for aerosol spraying a liquid product contained in a container, the method comprising the steps of: providing a container of the disposable type containing only the liquid product to be aerosol sprayed and provided with an aperture for feeding pressurised air, a valve for mixing the liquid product with air and a supplying nozzle; feeding pressurised air into the container in order to push the liquid product towards said valve for mixing the liquid product with said pressurised air so as to obtain an aerosol mixture; supplying said aerosol mixture with a constant pressure simultaneously to feeding into the container said pressurised air. 